Waning humoral immunity of SARS-CoV-2 vaccination in a rheumatoid arthritis cohort and the benefits of a vaccine booster dose

We aimed to assess SARS-CoV-2 spike-specific antibody kinetics postvaccination and the benefit of a mRNA vaccine booster dose in rheumatoid arthritis (RA) patients treated with immunosuppressive drugs. Consecutive RA patients on immunosuppressive therapies, with no known history of SARS-CoV-2 infection or high-risk contact, vaccinated with 2 doses SARS-CoV-2 mRNA, BNT162b2 or mRNA-1273, or viral vectored ChAdOx1 nCoV-19 vaccine were recruited during their routine rheumatology consultation. Anti-SARS-CoV-2 IgG spike-specific antibodies were quantified at 1, 3 and 6 months respectively following the second vaccine dose. The incidence of SARS-CoV-2 infection post-vaccination during this 6-month longitudinal study was also assessed. Of the 104 RA patients included, 79 patients completed the 6-month trial follow-up. A significant decrease in anti-SARS-CoV-2 spike-specific IgG titres was observed between 1-month and 3-month postvaccination (p